1. Field of the Application
The disclosure is directed to wireless communications and, more particularly, to fast scan algorithms for higher priority network or technology search in wireless communications.
2. Background of the Disclosure
Wireless communication systems are widely deployed to provide various communication services, such as: voice, video, packet data, circuit-switched info, broadcast, messaging services, and so on. A typical wireless communication system, or network, can provide multiple users access to one or more shared resources (e.g., bandwidth, transmit power, etc.). These systems can be multiple-access systems that are capable of supporting communication for multiple terminals by sharing available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, and so on.
Multi-access systems can be implemented via any number of radio access technologies (RATs) as defined in various network standards, such as Global System for Mobile Communications (GSM), Universal Mobile Telecommunication System (UMTS) and 3GPP Long Term Evolution (LTE). GSM and UMTS can be considered prior generation technologies and began as circuit switched (CS) systems. Generally, a CS network connection requires dedicated, point-to-point switches to establish the connection. LTE can be considered a more current generation of technology and is a packet switched (PS) system. Generally, a PS network does not require a dedicated, point-to-point connection, but instead a message gets broken into small blocks, or packets, each of which being able seek out the most efficient transfer route to the destination (i.e., each packet could take a different route to the destination). Usually, each current generation technology might be considered a higher priority technology than the prior generation (or generations) it replaces. For example, UMTS (as a third generation technology) might be considered a high priority technology than GSM (as a second generation technology), and LTE (as a fourth generation technology) might be considered a higher priority than either UMTS or GSM.
As new generations of wireless technology are rolled out, the prior generations and the current generations will co-exist for a period of time. Initially, LTE has been implemented for data transfer only, without voice capability (i.e., without an IP multimedia subsystem for voice over IP capability). Thus, an LTE-capable handset (HS) or mobile device must fall back (FB) to a previous generation RAT, such as GSM or UMTS, to make a voice call. Using CSFB, an LTE HS can make voice calls by reverting to traditional circuit switched communications.
Once a CSFB call has ended, the HS might be in a state that allows one or more applications (Apps) on the device to start or return to transferring data traffic while still on the lower priority network or technology, instead of first switching to a faster, more efficient or higher priority technology or network. For example, if the CSFB call is a UMTS call, once the call ends, the device might be in the UMTS cell-DCH (“dedicated channel”) or cell-FACH (“forward access channel”) state. While the mobile device is in either of these UMTS states, it may not scan for an LTE technology or a higher priority network, such as a high priority public land mobile network (PLMN), either of which might provide a user of the HS a faster and/or more efficient data traffic experience. Additionally, a mobile device might be connected (i.e., with an active radio link) in a lower priority network for any other reason, such as when roaming. In this situation, the device might be in a data traffic transfer state for one or more applications (Apps) that does not allow the device to scan for a higher priority technology or network, which might provide the user with a faster and/or more efficient data traffic experience.
Because there are more and more mobile device applications using data traffic, devices are likely to stay in or alternate between states on a lower priority technology or network for a long time and thus not switch back to a higher priority network or technology. Sometimes, the HS user may not even realize what is happening, because the data traffic could be initiated by one or more applications (Apps) running in the background of the device, potentially causing unnecessary delay in finding a higher priority technology or network.
Therefore, what are needed are techniques for fast scan for higher priority network or technology networks.